After my 1500 mile DC trip, I can focus on the Benz again.


Codes and review of current symptoms:

Pin (button) 2: code 10

Pin 8: 4,8,13,20 (Note: pin2 LED flashed simultaneously, but gave 10, 10, 13, 20)

Pin 14: 14


Current symptoms: occasional surging idle, low power/stumble on acceleration

Below are brief description of codes:

Pin 8
code 4 (Hot Film Mas Sensor)
code 8 (ISC at upper control stop/CC or EA indicates Limp home mode)
code 13 (Adaptation at limit)
code 20 (Self Adaptation at idle speed)

Pin 14
Code 14 (CTP Switch)

I would replace the CTP switch and see if that improves the surging idle, low power/stumble on acceleration.

The next step would be to replace the ECM with a known good one and see if that helps. if the Pin 8 code 4 comes back, you may have to replace the MAS.

In the worst case, you may have to replace the ISC/CC/EA, along with the ECM.

__________________
Zafar
94 E320 58000 Miles

Suspect is the MAF-- [ not mas].

You need a scan to check adaptation numbers for MAF testing..but,
You can go to pin 8 and clear codes til you get a single flash [all codes cleared].

After you get a 1, then you wait 2 secs, press button 8-9 secs,
turn key off for 30 secs , back on for 10 secs and start car.
This clears the adaptation memory back to zero [mean] .
Now monitor for codes every few trips and if 4 is the first one to pop up , I would change the MAF
On the CTP, I would make sure the cable is not sticking and there is a little slack in it at idle...

You may also want to slice into the wire harness for a look see...

As always, Arthur's analysis is excellent.

Hirnbeiss,

I have a good MAF, it has about 60K miles on it. Works Fine. I had replaced the one on my car for testing and turned out that it was the ECM.

Send me an e-mail if interested.

__________________
Zafar
94 E320 58000 Miles

And the winner is ......

(drum roll, please)



MAF!

After clearing the codes on pin 8, the first ones to reappear were:

4 MAF
13 Adaptation at limit

And, I guess it's reasonable for a hot film sensor to burn out after 160,000 miles (250,000 km).

Thanks for all the diagnostic tips!

Tom

HI !
i have an 88 300E that has that very famous stumbling and surging idle' problem,my car tends to stall at times after reaching normal operating temperature,stalls when i'm sitting at the light or even when coasting to a stop or at low speeds sometimes.it idles low and sometimes i see the R.P.M gauge dropping slowly to a stall. to restart it ,i have to crank it 2 or 3 times but end up depressing the accelerator so it would stay running.I increased the idling by adjusting it from the knob at the throttle cable and now it doesn't stall as much but runs at very high R.P.M's when not acting up.
i have replaced the I.C.V ,plug cables ( bosch),installed bosch 4 prong plugs without any results and i'm ready to throw a new overload relay at it.i hope this will do the trick.
what is MAF and do i have one on 88 300E?
is the OVP the overload relay?
i checked my fuel pump relay,i opened it and everything looks fine , no rust or loose parts there is a stamped date on it ,16/01/1998,does it mean the previous owner changed it already?
i would appreciate any input you have on this,any help would be welcome.
my car has 170k miles on it and the overload relay could be the original, it also has a date stamped on it 22/10/87.
my car was made in 12/87,but it's an 88 model.when buying parts do i search under 87 or 88.
ps; this web site is the best i have seen and the people are very helpfull
thank you very much
hamdane

Replaced the MAF last night and the car is back to normal. All codes cleared and none recurred.



Th '88 is definitely a different injection system (Jetronic??). I don't know how you read codes out on it.
Tom